Disclosure document No. 431,981 describing the invention was filed with the U.S. Patent Office on Feb. 14, 1998.
This invention relates generally to improvements in apparatus for production of three-dimensional (3D) objects. More specifically, it relates to apparatus for forming 3D objects using selective irradiation of radiation-curable materials (RCM). In response to radiation, RCM materials solidify or form 3D geometries with altered properties that allow by subsequent postprocessing (mechanical, chemical, thermal, etc.) to separate irradiated and nonirradiated portions from each other yielding a 3D object.
The field is usually referred to as rapid prototyping, freeform fabrication, desktop manufacturing, automatic fabrication or solid imaging. Most of the processes in the field build 3D objects in slices, one atop another. The slices are very thin so that object surfaces are reproduced with good approximation. Generally, slice geometry is derived by slicing object""s 3D model using computers and slices are formed by irradiating layers of RCM materials in areas where solidification is needed.
In xe2x80x98simultaneousxe2x80x99 processes (my U.S. Pat. Nos. 4,752,498; 4,801,477; 5,135,379 and 5,171,490) the whole slice is formed simultaneously, either by flooding irradiation through a pattern having transparent areas, like a photographic negative (mask) or electronically controlled transmission array (liquid-crystal display LCD, e.g.), or using an array irradiation source containing a large number of small light-emitting diodes LED, lasers, reflecting mirrors or cathode-ray tubes CRT, emitting numerous beams of radiation of very small cross-section. In xe2x80x98scanningxe2x80x99 processes (U.S. Pat. No. 4,575,330 of Charles Hull), each slice is formed by fast point by point scanning with a laser beam.
Since to achieve high dimensional accuracy many layers are formed, especially for thick objects, one of the most critical steps of any such process is deposition of very flat thin layers of RCM material that has to be fast, simple and lending itself to automation. In my U.S. Pat. No. 5,171,490 disclosed are deposition methods and means based on using a flexible film in contact with RCM material and a flat radiation-transmittent plate in contact with the opposite side of the film.
The primary objects of this invention are to provide improved apparatus for making 3D objects in layers, one atop another, using irradiation of radiation-curable materials (RCM). This is accomplished by using a flexible radiation-transmitting film one end of which is held at the layer formation level and the other at the film separation level, and a carriage in between to provide a moveable transitional area of the film. The carriage contains a wet guide at the separation level on the inner, wet side of the film and a dry guide on the external, irradiation side of the film, and means for depositing RCM material onto the inner side of the transitional area of the film. When the carriage moves in one direction, the material is being deposited onto the inner side of the film and at the same time the film with a layer of material on it is being laid down into irradiation position. Upon irradiation the carriage moves in the opposite direction gently separating the film from the formed object and at the same time cleaning the film from the material remaining on it.
In apparatus employing a container, simple and fast automatic deposition of flat layers covered with film, as well as nondistortive film separation with simultaneous cleaning are achieved by forming and irradiating layers at least partially above the container. This provides a gap between the container and film allowing excess material to escape and thus form a flat layer.